let list = [];
let tmp1 = "";
let tmp2 = "";
let tmp3 = "";
let tmp4 = "";
for (let i = 0; i <= 23; i++) {
  if (i < 9) {
    if (i == 0) {
      tmp1 = "0" + i + ":00";
      tmp1 = "0" + i + ":15";
      tmp2 = "0" + i + ":30";
      tmp3 = "0" + i + ":45";
    } else {
      tmp1 = "0" + i + ":00";
      tmp2 = "0" + i + ":15";
      tmp3 = "0" + i + ":30";
      tmp4 = "0" + i + ":45";
    }
  } else {
    tmp1 = i + ":00";
    tmp2 = i + ":15";
    tmp3 = i + ":30";
    tmp4 = i + ":45";
  }
  if (i == 0) {
    list.push(tmp1);
    list.push(tmp2);
    list.push(tmp3);
  } else if (0 < i < 24) {
    list.push(tmp1);
    list.push(tmp2);
    list.push(tmp3);
    list.push(tmp4);
  }
}
// list.push("24:00");
console.log(list);
